In a discovery that overturns conventional wisdom about bats, researchers have found that Old World fruit bats -- long classified as 'non-echolocating' -- actually do use a rudimentary form of echolocation. Perhaps most surprisingly, the clicks they emit to produce the echoes that guide them through the darkness aren't vocalizations at all. They are instead produced by the bats' wings, although scientists don't yet know exactly how the bats do it.